Roller pump with lubricating channels for rollers

ABSTRACT

A roller pump of the type having a flexible tubular pumping chamber continuously and successively depressed unidirectionally by traveling rollers wherein means is provided for directing cleaning and/or lubricating fluids to the bearing surfaces of the rollers to reduce wear and unnecessary &#39;&#39;&#39;&#39;drag&#39;&#39;&#39;&#39; on the tubular pumping chamber and insure that the longitudinal tension in the tubular chamber does not exceed a value which prevents lateral flexure and causes pumping action to continue rather than &#39;&#39;&#39;&#39;bypass&#39;&#39;&#39;&#39; when a resistance of predetermined magnitude is encountered.

United States Patent [72] inventor Robert E. Pickup Norrlstown, Pa.

[2]] Appl. No. 27,316

[22] Filed Apr. 10, 1970 Nov. 23, 1971 Extracorporeal Medical Specialties, Inc.

[45] Patented [73] Assignee [54] ROLLER PUMP WITH LUBRICATING CHANNELS FOR ROLLERS 3 Claims, 4 Drawing Figs.

[52] U.S.Cl 417/477, 308/l 15 [51] Int. Cl ..F04b 43/08, F04b 43/12. F04b 45/l6 [50] Field of Search 417/474.

[56] References Cited UNITED STATES PATENTS 2.4011485 417/477 8/1946 Arnold l.77l,937 7/1930 Pettit 308/113 3,172,367 3/1965 Kling... 4l7/477 $502,034 3/1970 Pickup 417/477 X Primary Examiner-Carlton R. Croyle Assistant Examiner-R. E. Gluck A!l0rneyConnolly and Hutz ABSTRACT: A roller pump of the type having a flexible tubular pumping chamber continuously and successively depressed unidirectionally by traveling rollers wherein means is provided for directing eleaning and/or lubricating fluids to the bearing surfaces of the rollers to reduce wear and unnecessary drag on the tubular pumping chamber and insure that the longitudinal tension in the tubular chamber does not exceed a value which prevents lateral flexure and causes pumping action to continue rather than "by-pass" when a resistance of predetermined magnitude is encountered.

BACKGROUND OF THE INVENTION The claimed invention relates to the field of power driven pumps used to convey fluids wherein the fluid being pumped is forced through a flexible tubular chamber by pumping members mounted for travel in unidirection depressing contact with the tubular chamber. Pumps of this general type are capable of a wide variety of uses, but are particularly useful in pumping sensitive fluids-such as blood, parenteral infusion liquids, and the like-at slow, carefully controlled rates and pressures in critical environmental settings such as those encountered in the medical profession.

Prior to the present invention, pumps of this general nature have been used for many years. Arnold US. Pat. No. 2,406,485 illustrates the basic principle of using a flexible tubular pumping chamber stretched over triangularly arranged rollers on a power rotated head, and the most advanced type of such pump heretofore commercially available is disclosed in my US Pat. No. 3,502,034. Pumps of this type, where the tubular pumping chamber is not trapped against an outer wall but is simply stretched around the pumping members and is otherwise unsupported, have a relief valve" feature which is advantageous in many instances. If the fluid being pumped meets with abnormally high resistance, such as a clogged line downstream from the pump, the flexible pumping chamber is capable of expanding despite the continuing rotation of the pumping members, and the lateral expansion will permit the pumping action to be discontinued preventing rupture of the system. As one example, when a pump of this nature is utilized to deliver fluid to a patient in an intravenous feeding operation, it occasionally occurs that the fllter downstream of the ump becomes clogged with material which apparently crystallizes out of the fluid being pumped, and pumps of this type will discontinue pumping action when a resistance of predetermined value builds up rather than continuing the pumping action and driving the undesirable crystallized material through the filter and into the patient.

One problem with pumps heretofore available, however, is that this relief valve feature is erratic and unpredictable, and the pump may discontinue its pumping action in the desired fashion against a resistance of predetermined value on one day, but on the next day will undesireably continue pumping against a greatly increased resistance. It is believed that this is due in part to the rollers of the pumping members freezing" on their spindles, as by contaminants clogging the bearing surfaces, which causes the stuck roller to drag on the inflow portions of the tubular pumping chamber. This is believed to create longitudinal tension in the tube to the point where its ability to flex and expand laterally, and thereby bypass fluid to be pumped, is inhibited. Rollers which lock on their spindles also create other equally serious problems, such as increased wear on the tube. If the pump drive is equipped with a low-torque safety clutch, moreover,jammed rollers can create sufficient drag that the clutch activates, permitting the pumping rotor to stop while the drive motor continues unimpeded, resulting in motor bum-out. If the pump is a battery operated unit, the increased drag caused by rollers which do not turn freely draws excessive power and reduces the battery cycle causing the unit to fail prematurely-which the patient can ill-afford if replacement batteries are not readily at hand.

Prior attempts to solve this long recognized problem and insure that the pumping rollers turn freely on their spindles make use of the obvious expedient of utilizing more expensive bearing equipment. For instance, Santiago US. Pat. No. l,988,337 and Jones US. Pat. No. 2,334,148 disclose the use of ball bearings; Moulinier US. Pat. No. 2,483,924 and Ballentine US. Pat. No. 3,402,673 disclose the use of sleeve bearings; and, Jensen US. Pat. No. 2,696,l73 discloses the use of collar bearings. All these, however, are susceptible of clogging and jamming. for instance. when fluid being pumped or other contaminants get into the bearings, and they are ex- I wherein similar reference characters refer tremely difiicult to disassemble and clean. Thus, these expedients do not get at the heart of the problem of providing means to insure that the pumping rollers turn freely to overcome the aforementioned difficulties.

Thus, the problem heretofore unsolved by the prior art is the provision of simplified means for directing cleaning and/or lubricating fluids to the bearing surfaces of the rollers to reduce wear on the tube and insure that the relief valve feature of the pump functions predictably rather than erratically.

SUMMARY OF THE INVENTION This invention provides a roller pump of the type having a resilient tube anchored between an inflow station and an outflow station and at least one pumping member mounted for travel in unidirectional depressing contact with the tube along a portion of its length, the pumping member including a traveling spindle having an outer bearing surface, a tube-contacting roller having an inner bearing surface mounted on the spindle, and channel means for delivering cleaning and/or lubricating fluids to the bearing surfaces. The channel means comprises a hole in the spindle which communicates at one end with the bearing surfaces and at the other end with the opposite or clean side of the rotor to receive cleaning and/or lubricating fluids from a source such as a hypodermic needle for delivery to the bearing surfaces. To this end, the rotor is releasably secured to the base by a spring-loaded detent arrangement so it can easily be removed and held upside-down while the cleaning and/or lubricating fluids are applied.

BRIEF DESCRIPTION OF THE DRAWINGS Numerous advantages of the present invention will become apparent to one skilled in the art from a reading of the detailed description in conjunction with the accompanying drawings to similar parts and in which:

FIG. 1 is a front perspective view of a roller to this invention;

FIG. 2 is a fragmentary plan view showing the positioning of the pumping rollers on the pump of FIG. 1;

F IG. 3 is an enlarged fragmentary sectional elevational view on line3-3 of FIG. 2 showing the channel means in the spindle ofa pumping member; and,

FIG. 4 is a fragmentary view ofa pumping member held upside-down for the application of cleaning and/or lubricating fluids.

pump according DETAILED DESCRIPTION Referring in more particularity to the drawings, the roller pump unit 10 illustrated in FIG. 1 comprises a main housing 12 having an instrument panel 14 secured to the front face and a foldable handle 16 secured to the top. The main housing 12 contains an electrically powered drive motor, a speed reduction gear box, optionally a low-torque clutch, speed indicating mechanisms, and other related controls which per se form no part of the present invention. A rotatable drive shaft 18 protrudes vertically upwardly through the top of the housing 12 for connection with the pumping member rotor, as explained below.

Mounted on top of the housing 12 is pump head 20 which comprises a lower tube anchoring block 22 on one side, an upper tube anchoring block 24 of the other side, and therebetween a power driven rotor 26 having three eccentrically spaced pumping members 28. The lower tube anchoring block 22 holds both ends of a resilient pumping tube 30 which in turn is connected to an inflow conduit 32 and to an outflow conduit 34. The upper tube anchoring block 24 holds both ends of another resilient pumping tube 36 which in turn is connected to an inflow conduit 38 and to an outflow conduit 40. Details of the construction of the tube anchoring blocks 22, 24 are disclosed in my aforesaid patent 3,502,034 to which specific reference is made for details of the inflow station 42 and outflow station 44 on the upper tube anchoring block 24 and the inflow station 46 and outflow station 48 on the lower tube anchoring block 22.

The rotor 26 comprises a single circular plate portion 50 with an upstanding central boss 52 having an axial aperture 54 to receive the upper end of the power driven shaft 18. A spring loaded detent arrangement 56 in the boss 52 laterally engages as at 58 the upper end of the shaft 18 to prevent accidental axial displacement of the rotor 26 from the shaft [8. The aperture 54 in the rotor includes a flat 60 or other keyway arrangement which cooperates with a corresponding flat 62 on the shaft 18 to insure that the rotor and the shaft turn together. The aperture 54 in the rotor does not extend through the top of the upstanding central boss 52, which may have a smooth upper surface preventing any accidental leakage of fluid along the shaft 18 and into the housing 12.

The three pumping members 28 take the fonn of rollers or spools 64 having generally cylindrical inner bearing surfaces 66. The rollers are mounted for free rotation on spindles 68 having generally cylindrical outer bearing surfaces 70. The spindles 68 are preferably of stainless steel, and are mounted eccentrically of the shaft 18 on the upper side of the flat plate portion 50 of the rotor, such as by a reduced diameter shank portion 72 received with a press fit in a suitable vertical aperture in the plate portion 50 and flared outwardly as at 74 to engage a countersunk portion of the aperture on the lower side of the plate portion. The rollers 64 are preferable machined from polyoxymethylene, such as the commercially available Delrin", to provide first 76 and second 78 axially spaced tube depressing portions, each portion having a convex tube centering configuration. The lower convex portions 76 insure that the lower pumping tube 30 is properly mounted in a lower plane perpendicular to the rotor axis and spaced slightly below the upper parallel plane occupied by the upper pumping tube 36 trained around the upper convex portions 78 of the rollers 28.

Each pumping member 28 includes channel means for delivering cleaning and/or lubricating fluids to the bearing surfaces 66, 70. The channel means comprises a hole 80 in the spindle 68 communicating at one end 82 with the bearing surfaces and accessible at the other end 84 to the atmosphere in the zone where each spindle is secured to the rotor so as to be accessible to a source of fluid, such as a hypodermic needle. Preferably, the lower end 84 of the hole communicates with the atmosphere on the opposite side of the rotor from the rollers 64 to minimize the possibility of contaminants from the pumping tubes reaching the bearing surfaces. The hole 80 extends generally axially of the spindle from the lower end 84 thereof to a point near the bearing surfaces 66, 70, and then extends laterally of the spindle to communicate with the bearing surfaces as at 82.

The pumping tubes 30,36 are similar, although tubes of different diameters may be utilized to pump two different fluids at two different rates simultaneously. The pumping tubes are preferably molded to length of silicone rubberfand are extremely resilient having ability to expand and permit the relief valve" feature described above. For pumping low volumes of fluid, the portions of the tubes contacted by the roller may be molded of smaller diameter than the ends of the tubes which cooperate with the slots at the inflow and outflow stations, as is apparent. When two tubes 30, 36 are employed and anchored in the opposite blocks 22.24, unbalanced lateral stress on the rotor axis is minimized or eliminated, and each roller 64 rotates constantly about its spindle 68 insuring that it is rotating with the proper peripheral speed each time it moves into contact with the inflow portion of a pumping tube.

in operation, power operated rotation of the rotor 26 (counterclockwise in FIG. 2) serves to move fluid through the pumping tubes 30,36 pumping it from the inflow conduit 46 to the outflow conduit 48, and from the inflow conduit 38 to the outflow conduit 40, respectively. At the end of each period of use, especially if there is a likelihood that contaminants or other foreign matter may have seeped into the bearing surfaces 66, 70 between the rollers and the spindles 68 it is a simple matter-after removing the pumping tubes 30, 56-to grasp the rotor 26 and remove it axially from the drive shaft 18. Holding the rotor upside-down, see FIG. 4, cleaning and/or lubricating fluids may be applied by a hypodermic needle to the inlet end 84 of the hole $6 for delivery as at 82 to the bearing surfaces. A015 through 018 gauge blunt end hypodermic needle may be used for this purpose. If the pumping members are particularly clogged or jammed, a cleaning fluid such as alcohol or acetone may first be injected to flush out the contaminants. A lubricating fluid such as castor oil has been found particularly useful for insuring that the polyoxymethlene rollers 64 turn freely on the stainless steel spindles 68.

There has thus been disclosed a means for insuring that the rollers of the pumping members turn freely on their spindles, minimizing the various problems created by rollers which tend to freeze" on their spindles.

While the above described embodiment constitutes the presently preferred mode of practicing this invention, other embodiments and equivalents are included within the scope of the actual invention, which is claimed as:

l. A pump comprising a base, a drive shaft mounted for continuous rotation relative to the base, a power driven rotor comprising a plate portion, an axial apperture in the plate portion for receiving one end of the drive shaft, a detent arrangement for releasably securing the rotor to the drive shaft, and a plurality of pumping members secured to an eccentrically spaced on the rotor, each pumping member including a spindle secured at one end to the plate portion of the rotor and having an outer bearing surface, a tube-contacting roller having an inner bearing surface mounted on each spindle, a resilient tube anchored between an inflow station on the base and an outflow station on the base and stretched around the pumping member rollers so that it is otherwise unsupported between the inflow station and the outflow station, and channel means comprising a hole in each spindle communicating at one end with the bearing surfaces and at the other end with the atmosphere on the opposite side of the rotor to minimize the possibility of contaminants associated with the roller side of the rotor from reaching the bearing surfaces via the hole, the hole being of a diameter susceptible of receiving cleaning and/or lubricating fluids from a source such as a hypodermic needle for delivery to the bearing surfaces.

2. A pump as in claim 1 wherein the rollers each have first and second axially spaced tube-contacting portions each such portion having a convex tube-centering configuration.

3. A pump as in claim 2 wherein the inner bearing surface of each roller is generally cylindrical, and each roller is machined from polyoxymethylene. 

1. A pump comprising a base, a drive shaft mounted for continuous rotation relative to the base, a power driven rotor comprising a plate portion, an axial apperture in the plate portion for receiving one end of the drive shaft, a detent arrangement for releasably securing the rotor to the drive shaft, and a plurality of pumping members secured to an eccentrically spaced on the rotor, each pumping member including a spindle secured at one end to the plate portion of the rotor and having an outer bearing surface, a tube-contacting roller having an inner bearing surface mounted on each spindle, a resilient tube anchored between an inflow station on the base and an outflow station on the base and stretched around the pumping member rollers so that it is otherwise unsupported between the inflow station and the outflow station, and channel means comprising a hole in each spindle communicating at one end with the bearing surfaces and at the other end with the atmosphere on the opposite side of the rotor to minimize the possibility of contaminants associated with the roller side of the rotor from reaching the bearing surfaces via the hole, the hole being of a diameter susceptible of receiving cleaning and/or lubricating fluids from a source such as a hypodermic needle for delivery to the bearing surfaces.
 2. A pump as in claim 1 wherein the rollers each have first and second axially spaced tube-contacting portions, each such portion having a convex tube-centering configuration.
 3. A pump as in claim 2 wherein the inner bearing surface of each roller is generally cylindrical, and each roller is machined from polyoxymethylene. 